Concrete masonry units are available in a wide range of sizes and shapes, and are used for a variety of applications, ranging from concrete blocks and bricks to segmented wall blocks.
Generally, masonry units are produced using an automated process. The typical automated process for producing the units includes placing a mold, which is open at the top and bottom, on a solid pallet. The mold is then filled with a suitable composite material (generally comprising concrete and aggregate material). Next, the filled mold and/or pallet may be vibrated while the material is simultaneously compacted within the mold using a compression head inserted into the top of the mold to increase the density of the composite material. The molded composite material may then be stripped from the mold (while still resting on the pallet) and cured to form a building unit such as, but not limited to, a brick or a paver block.
Often, it is desirable to produce masonry units having at least one tapered vertical edge (e.g., the width of the top of unit is different from the width of the bottom of the unit). These masonry units are generally produced using a mold having one or more angled side walls. However, stripping the molded composite material from these molds is difficult because the side walls must be moved away from the composite material before the molded unit may be removed from the mold. Therefore, special molds are typically used to create tapered masonry units.
One prior attempt at creating tapered masonry units has been to use a “tilt-over” mold, such as the apparatus described in U.S. Pat. No. 4,735,562 to Boutellier. Tilt-over molds are inverted during the filling and forming process and are then turned over to remove the molded unit. However, tilt-over molding requires complex machinery and results in longer production times. Further, turning the mold upside down can damage the inverted face of the finished unit, which is typically not completely cured during the de-molding step. Because damaged units are normally rejected, manufacturing prices are increased.
Another technique involves the use of a mold having product-forming walls that may be retracted away from the molded unit. Such retractable walls are typically actuated in multiple directions by hydraulically and/or pneumatically operated machinery which may be bulky and which may require separate power and controls. Such arrangements add complexity and cost to the manufacturing process. They also reduce the usable mold space, thereby yielding fewer finished units per manufacturing cycle.
Yet another attempt at creating tapered masonry units has been to use hinged walls which are pivotally connected at a point within the mold cavities. In this technique, as the mold is placed on a pallet, the walls may be forced into an angled position, thereby creating a mold having a tapered edge. However, this technique has been found to be unsuitable because the hinged walls may pivot out of position during the vibrating step discussed above. As a result, the tapered walls of the masonry product may become deformed and unusable.
Therefore, a less complex, cost-effective apparatus and method for creating high quality tapered products is desirable.